Manometric apparatus for determining the gas content of liquids



'Dec. 11, 1956 D. E. KING ETAL MANOMETRIC APPARATUS FOR DETERMINING THEGAS CONTENT OF LIQUIDS 2 Sheets-Sheet 1 Filed Nov. 19, 1953 I .2 J8 DIMEK Dec. 11, 1956 D. E. KING ETAL 2,773,747

MANOMETRIC APPARATUS FOR DETERMINING THE GAS CONTENT OF LIQUIDS FiledNov. 19, 1953 2 Sheets-Sheet 2 MANOMETRIC APPARATUS FOR DETERMENING THEGAS CONTENT OF LIQUIDS Duncan E. King, Wayne, and Joseph A. McNeilly,Plymouth Meeting, Pa., assignors to Arthur H. Thomas Company,Philadelphia, Pa., a corporation of Pennsylvania Application November19, 1953, Serial No. 393,181

1 Claim. (Cl. 23-253) The present invention relates to clinicalapparatus and has particular application to manometric apparatus inwhich a body fluid i agitated with given reagents under reduced pressureto determine certain physical or chemical properties of the body fluid.

In clinical apparatus of the type for determining the gas content ofblood, the blood is mixed with chemical reagents in an extractionchamber and agitated to drive off the gas contained in the blood. Inconventional apparatus, to provide for agitation for blood in theextraction chamber, the extraction chamber and its associated apparatusare vibrated. To this end, the apparatus is mounted on a hinged backingplate which is connected to an eccentric driven by an electric motor.Apparatus of this character is not entirely satisfactory since thevibration necessitates reinforcement of the fragile tubes andconnections to reduce the possibility of breakage. In addition, thevibration of the backing plate has a tendency to cause the apparatus towalk on the laboratory bench and to overcome this tendency, it isnecessary to bolt or otherwise clamp the apparatus to the bench. Thismethod of agitation is also wasteful of power since the motor forcausing the agitation, must vibrate the whole apparatus.

With the foregoing in mind, a primary object of the present invention isto provide, for agitating body fluids with reagents, clinical apparatuswhich obviates the necessity for vibrating the apparatus itself.

Another object of the present invention is to provide clinical apparatusfor extracting gas from blood and like fluids in which the extractionchamber is fixedly mounted on a stationary stand, and agitation isaccomplished by an element contained in the chamber.

A further object is to provide apparatus of the stated type which iseconomical of power and is of simple and inexpensive construction.

More specifically, the invention-contemplates clinical apparatus havingan extraction chamber in which a magnetized element is contained forfree rotation under the action of a rotating magnetic field.

Another object of the invention is to provide apparatus having thefeatures and characteristics set forth which is fully eflicient andeffective in operation and use.

These and other objects of the invention and the various features anddetails of the construction and operation thereof are more fully setforth hereinafter with reference to the accompanying drawings in which:

Fig. 1 is a perspective view of blood gas testing apparatus embodying anagitator made in accordance with the present invention;

Fig. 2 is a fragmentary front elevational view of the apparatus shown inFig. 1;

Fig. 3 is a side elevational view partially in section of the apparatus;

Fig. 4 is a detached fragmentary perspective view of the extractionchamber showing the operation of the agitator;

nited States Patent ice Fig. 5 is a sectional view of the extractionchamber embodying a magnetic agitator made in accordance with thepresent invention; and

Fig. 6 is a sectional view of the agitating element.

Referring now to the drawings, the blood gas testing apparatusillustrated therein comprises a casing 11 which mounts thereon by meansof spring clip 9 which is secured to casing 11 by bolt 10 an extractionchamber 12 having gas-measuring pipette 13 formed integrally therewith.The extraction chamber 12 is maintained under a given pressure by amercury column 14 and to this end is closed at the top by a stop cock20. The mercury is supplied from a reservoir 15. Thus, a flexible tube16 extends to a bent connecting tube 36, which is of glass, the flexibletube 16 being slip-fitted over the lower open end of bent connectingtube 36. Connecting tube 36 is carried on casing 11 by means of springclips 37 and is supported by means of angle flanges 38, which arepreferably encased in rubber or other resilient elastomeric material toprovide cushioning against shock and the like.

Connecting tube 36 is generally in the shape of a cross with thehorizontal arms of the cross being bent into the form of U-arrns. Stopcocks 39 and 40 are provided in the vertical arms of the connecting tube36, and each of the U-arms 41 and 42 are connected by respective groundglass ball-and-socket joints 43 and 44 to graduated tube 14 and toextraction chamber 12. Graduated tube 14- constitutes a manometer forindication of pressure in the system. The ball and socket joints areheld in gas-tight seal alignment by means of conventional pinch clamps45 and 46 respectively. The height of the column of mercury withingraduated tube 14 may be regulated by raising or lowering the mercuryreservoir 15, thereby regulating the pressure within extraction chamber12.

In accordance with the usual practice, blood and the desired reagents,indicated at 17, are floated on the mercury 18 in the extractionchamber. A water jacket 19 surrounds the extraction chamber 12 and thepipette 13 to maintain a constant temperature during the agitation ofthe liquid. In the present instance, the water jacket 19 is closed, butit is within the'scope of the invention to provide tubulatures at thetop and bottom of the jacket for admitting and discharging a constantstream of water.

In accordance with the present invention, a magnetic agitating element21 is contained in the extraction chamber. As seen in Fig. 6, theagitating element 21 comprises a bar magnet 22 having a coating 23 whichis non-reactive with the blood and reagents. The coating 23 must also benon-magnetic so that it will not shield the magnetized element 22 fromthe magnetic field.

The element 21 is free to be rotated in the extraction chamber by arotating magnetic field. In the present instance, the rotating magneticfield is provided by a permanent magnet 25 mounted on the shaft 26 of amotor 27. The motor is mounted in the casing on a suitable bracketmember 28, as clearly illustrated in Fig. 3. As the motor rotates themagnet 25, a rotating magnetic field is created to act upon theagitating element 21 in the extraction chamber. The field causes theelement 21 to rotate and agitate the liquid 17 to drive off the gascontained therein. Thus, the liquid is agitated in an extraction chamberthat is rigidly mounted on the casing, and the invention obviates thenecessity for vibrating the chamber and the casing.

It is desirable to illuminate the extraction chamber and the pipette tofacilitate accurate operation of the apparatus. To this end, a lamp 3!is mounted in the casing 11. An opening 31 is provided behind thepipette 13 and a translucent plastic window 32 is secured over theopening to illuminate the pipette 13 and exclude dirt and other foreignmaterial from the casing. A similar opening 33 is provided between themagnet 25 and the extraction chamber 12 and is also covered by a plasticWindow 34. It is noted that the window 34 is mounted to slant outwardlyof the casing to provide a vent for admission of air to the interior ofthe casing A switch is provided at 34 for controlling the light 30 and amotor speed control rheostat 35 is provided for controlling the speed ofthe motor and thereby the amount of agitation afforded by the agitatingelement 21.

' Inasmuch as both the extraction chamber 12 and the bent connectingtube 36 remain stationary during use, it is possible to secure them tothe'casing 11 in the manner indicated, namely by the spring clips 9 and37. Moreover, the bent connecting tube may be secured by theball-and-socket joints 43 and 44 to the graduated tube 14- and to theextraction chamber 12. The use of spring clips and ball-and-socketjoints permits the rapid assembly, cleaning, disassembly, andreplacement of the component elements of the subject invention. Incontradistinction, slip-fitted elastomeric material connections, such asthe rubber stoppers and hoses used in all prior manometric apparatus formeasuring the gas content of V liquids, are frequently exceedinglydifiicult to disassemble, clean, and assemble.

The use of a magnetic stirrer with spring clips and ball-and-socketjoints permits the flexible apparatus embodiment of the subjectinvention, since the need for secure anchorage concomitant to priordevices involving the use of shaking apparatus is avoided.Notwithstanding the use of spring clips in place of more rigid anchorage means, and reinforcement means the incident of breakage in use ismarkedly decreased, since the apparatus is subjected to far less stressand strain. All of the foregoing is accomplished without any loss inaccuracy whatsoever. In fact, as a practical matter, due to the ease ofcleaning attendant to the subject apparatus, the

accuracy of the apparatus is improved, since a major source of error inuse arises due to contamination resulting from infrequent or carelesscleaning.

By virtue of the ease of disassembly of the subject apparatus, and byvirtue of the substitution of shaking by magnetic agitation directlyWithin the fluid, the subject apparatus may be made smaller in size toaccomplish a given task and is therefore more portable than priorrebeenherein illustrated and described, it is not intended to limit theinvention to such disclosure, and changes and modifications may be madetherein and thereto within the scope of the following claim.

We claim:

A manometric apparatus for ascertaining the gas content of a liquid ofthe Van Slyke type including in combination a casing, an extractionchamber, a gas measuring pipette extending upwardly from said extractionchamber, stop cock means at the upper extremity of said 7 gas measuringpipette, means defining a jacket around said extraction chamber and gasmeasuring pipette for maintaining the same at a substantially constanttemperature, a spring clip mounted to said casing, said spring clipresiliently operatively grasping said jacket means whereby saidextraction chamher is retained in vertical disposition, a graduated tubefor a column of mercury vertically mounted in respect to said casing, aconnecting tube beneath said extraction chamber and graduated tube,spring clip means secured to said casing and resiliently operativelygrasping said connecting tube and maintaining it in operative alignmentand in liquid communication in respect to said extraction chamber andsaid graduated tube, said connecting tube being operatively andliquid-tightly joined to said extraction chamber by a readilydisassembled ball-and-sock'et joint and operatively and liquid-tightlyjoined to said graduated tube by a readily disassembled ball-and-socketjoint, means for adjusting the height of mercury within said graduatedtube whereby the pressure Within said extraction chamber may beadjusted, said Water jacket, graduated column, extracting chamber, andpipette being formed of transparent non-magnetic material, a magnetizedelement comprising a permanent bar magnet having an inert coating, saidmagnetized element being disposed within the extraction chamber, a motormounted Within said casing with its rotary shaft extending intoproximity.to said extraction chamber, and a permanent magnet mounted on saidshaft operable upon rotation ofsaid shaft to create a rotating magneticfield to act upon said magnetized element and eiiect rotation of thelatter within the extraction chamber whereby liquid within theextraction chamber may be agitated.

Advertisement of the Emil Greiner C0,, Improved Van Slyke Apparatus,Journal of Chemical Education, Vol. 27 (October 1950), page 6 of theAdvertisers Section.

Noller et al.: Industrial and Engineering Chem., Analytical Ed, vol. 14(November 1942), pages 907-908. Schaar & C0., Selected LaboratoryEquipment]? Catalogue No. 50 (1950), page 616.

